Variable-resistance device.



W. C. REED.

VARIABLE RESISTANCE DEVICE.

APPLICATION FILED OCT. I6 I913 50 f o" 1 5K I.-I"

-l 24 46 48 7 i I 46 43 J0 ""2 I?" I Z 47 I ii 47 07 .1; F .fi .Jz 7 A7 52/ J5 /Z, 6 /2/ zfezwa e3 ,Z'iiz/wfioh' Qh fi. 3 Wm (9. m1,

OLLIMBIA PLANOGIZAIH :QAVASHINGTQN, D c.

Patented Sept. 7, 1915.

2 SHEETS-SHEET I.

W. C. REED.

VARIABLE RESISTANCE DEVICE.

APPLICATION FILED OCT. 16, 1913.

1,152,842. PatentedSept. 7, 1915.

Z SHEETS$HEET 2.

fizz/6738 52? Wm M,

COLUMBIA PLANOGRAPH co., WASHINGTON, D. c.

NITE STATES PATEWF WALTER C. REED, OF DALTQN, MASSACHUSETTS, ASSIGI'TOE Ti: TELELEOTRIG COM- Pnrir, or rrr rsrrnr n, n ssaoszusnrrs, a conronarron or MASSACHUSETTS.

VARIABLE-RESISTANCE DEVICE.

To all whom it may concern Be it known that I, WALTER G. Brno, a

citizen of the United States, residing at Dalton, in thecounty of Berkshire and State of Massachusetts, have invented new and useful Improvements in Variable-Resistance Devices, which the following is a specification. i

This invention, which relates to devices for varying the amount of resistance in an electric circuit, is particularly intended to provide a device of this character which will be suitable for use in connection with certain types of electricallyoperated piano players and, when so employed, will have various advantages over prior arrangements for the'purpose.

The particular form of device illustrated in the accompanying drawings is intended for use in a piano player in which the playing magnets are divided into two groups, each of which is provided with a controller magnet for regulating the current sent through the playing magnets in the correspondinggroup; In such an apparatus the circuit through each controller magnet includes a variable resistance, and the present device therefore has two such resistances, one for each controllermagnet. More or less than two such resistances may be employed, however, and since the two resistances illustrated are identical in structure the description of either one will apply to the other.

In the drawings, which illustrate my device as preferably constructed :Figure 1 is a diagram showing the electric circuits contained in and connected to the device; Fig. 2 is a side elevation of the device, with the outside circuits omitted; Fig. 3 is a longitudinal section on the line a:w in Fig. 4; Fig. 4 is a plan view of the parts shown in Fig.2, with the outside circuit leads added; and Fig. 5 is a transverse section on the line yy in Fig. 2.

Referring to the drawings, 2 indicates a base. plate carrying oneach side an upright frame 3 with insulating bars 4; and 5 secured thereto at its top and bottom. The upper bar 1 carries a number of metallic clips 6, which are connected in series through a number of resistance. coils 7 arranged vertically atone side of the open frame 3 and connected at their upper and lower ends respectively to wires 8 and 9, of which each wire 8 extends upward into contact with the corre Specification of Letters Patent.

Application filed October 16, 19,13.

' Patented Sept. Z, 1915.

Serial No. 795,591.

sponding clip 6 while the wire 9 passes downward to the insulating bar 5 and thence upward into contact with the next clip 6 in the series. .The lower portions of the wires 9 are heldvout of contact with one another by passing them under the heads of screws 10 entering the lower bar 5. By this arrangement a considerable amount of resistance is caused to occupy but a small amount of space, and provision is made for keeping the 13 to a like number of spring contact wires I 14 arranged in line one behind another and each bent to provide a pair of upright portions extending toward each other below their outwardly-turned upper ends, as shown at 15. The lower portions of the wires let are located in parallel grooves formed in an insulating block 16 secured to the base plate 2 but separated therefrom by a sheet of fiber 17, whereby said wires 14 are insulated from one another and held upright in spaced relation. These wires 14 cooperatewith a metallic blade 18 adapted to be moved upward and downward between and in contact with the opposed portions 15 of the wires 11, as hereinafter described, and so shaped that the number of wires 11 with which it is in contact at any given instant will depend upon its position of elevation. For example, when said blade 18 is in itsuppermost position it will make contact with all the wires 1, and hence the corresponding resistance coils 7 will be short-circuited, since the current can pass from oneof the corresponding metallic'clips 6 to another through the path of low-resistance afforded by the wires 13 and 1d and the blade 18in contact with the latter. When in its lowermost position the blade 18 will make contact with but one of the wires 14, so that none of the resistance will be short-circuited thereby, while in intermediate positions of said blade an intermediate amount of resistance will be shortcircuited, as will be obvious.

For'operating the blade 18 I provide a block 19 made of insulating material and mounted to oscillate on a horizontal pivot pin 20 carried by an upstanding support 21 secured to the base plate 2, to which block is secured an arm 22 carrying said blade at its free end. A fiber washer 23 interposed between the arm 22 and the support 21 completes the insulation of said arm, so that current cannot be transmitted from one arm 22 to the other. On opposite sides of the pivot pin 20 are located two electro-magnets 24 and 25, preferably of the solenoid type and of like power, with vertically movable plungers 26 and 27 arranged to operate on the block 19 in such manner that the two magnets 24 and 25 act in opposition to each other if both of them are energized simultaneously. Preferably this is accomplished by connecting the plungers 26 and 27 to the ends of a strip of leather 28 extending over the top of the block 19 and supported on a metallic plate 29 carried by said block, with the plungers sufficiently elevated to cause them to be pulled downward by their respective magnets when energized. This arrangement prevents noise in the operation of the parts.

The coils of the magnets 24 and 25 are each connected at one end to a common terminal 30 and at the other end to terminals 31' and 32 respectively, from which circuit wires 33 and 34 lead to corresponding contact fingers 35 and 36, which cooperate with a contact bar 37 and may be assumed to be under the control of a perforated music sheet. A circuit wire 38 connects the contact bar 37 to one pole of a source of current such as a generator 39, and another circuit wire 40 connects, the other pole of the generator to the terminal 30 and thus serves as a common return wire for both of the magnets 24 and 25. As thus constructed, whenever the circuit through the magnet 24 alone is closed at the contact bar 37, said magnet is energized and pulls the blade 18 downward to a position in which none of the resistance is short-circuited, as shown in Fig. 3. On the other hand, if the'magnet 25 alone is energized by the closing of its circuit at the contact bar, then the blade 18 is elevated to the maximum extent and four of the resistance coils 7 are thereby short-circuited, thus diminishing the resistance to a corresponding extent. If both of the magnets 24 and 25 are energized simultaneously, however, the arm 22 is caused to take an intermediate position in which the pull of each magnet balances the pull of the other, and the blade 18 then short circuits an intermediate amount of resistance. It will thus be seen that in order to cause the blade 18 to assume any one of three positions it will suffice to provide the music sheet with two lines of slots corresponding respectively to the positions of the fingers 35 and 36 at the contact bar, and since said blade has no tendency to move out of any position which it occupies it is merely necessary to close momentarily the circuit through one or both of the magnets 24 and 25 in order to operate the blade as may be desired, and hence the employment of long slots in the music sheet is obviated.

Since the blade 18 is capable of assuming but three different positions under the influence of the magnets 24 and 25 there would be no reason for providing more than three of the wires 14 so far as the result of the operation of said magnets is concerned, but the employment of more than three such wires is desirable in order to enable corresponding gradations of resistance to be obtained by manual operation of said blade. This is provided for, in the construction illustrated, by securing to the topof the block 19 arm 41 having a counterweight 42 at one end and a pin 43 at its other end, which pin may serve as a handle for manual operation or may be connected to any suitable form of operating device. Felt-faced stops 44, which are located respectively above andbelow the arm 41 and are adjustably secured to an upright rod 45 secured to the base plate 2 and passing through a slot in said arm, serve to limit the upward and downward movements of the blade 18. It will be seen that the construction above described leaves the blade 18 free to be manually operated at any time, and that said blade becomes subject to operation by the magnets 24 and 25 as soon as it is released from manual control.

The operation of the parts above described will evidently result in varying both of the resistances simultaneously and similarly, and will therefore affect all the playing magnets in connection with which these resistances are employed, assuming that such magnets are divided into two groups. It is usually desirable, however, to provide for varying the resistance used in connection with one group of playing magnets only, and to this end one or more normally-open shunt circuits may be employed in connection with each resis ance, whereby either re sistance may be varied without affecting the other. These shunt circuits may be arranged to short circuit either a portion of the resistance which is subject to the control of the blade 18, or an additional portion of the resistance not subject to such control. Both arrangements are diagrammatically illustrated in Fig. l of the drawings, in which 46 and 47 indicate circuit wires connected respectively to two of the clips 6 which are not connected to the wires 14, while 48 indicates another circuit wire connected to an intermediate clip 6 and adapted to be placed in electrical communication with either or both of the wires 46 and 47 by means of independent circuit closers 4L9. and 5,0,at which the corresponding shunt circuits are normally open. An-

.other shunt circuit is provided" by wires 51 position, except that said shunt circuit effects but one of theresistances, While the effect of the first-mentioned shunt circuitswi-ll be independentof and supplementary to that produced by the operation of saidblade.

Various forms-and arrangements of variable resistances, shunt circuits and other details may be employed instead of those above described, if preferred, and the resistance may be divided into any desired number of portions each having any desired resistance capacity, as will be evident.

I claim:

1. The combination with an electric circuit having a variable resistance included therein, of means for varying said resistance comprising a movable contact device, an electro-magnet for moving the same into one of its extreme positions, another electromagnet for moving said contact device into its other extreme position, said magnets being arranged to move said device into an intermediate position when energized simultaneously, and means for closing the circuits through said magnets either singly or simultaneously.

2. The combination with two independent electric circuits each having a variable resistance included therein, of electricallyoperated means for simultaneously and similarly varying said resistance, and supplementary means for varying either of said resistances without afiecting the other resistance.

f 3. The combination with two independent electric circuits each having a variable resistance included therein, of a movable contact device for varying each resistance, an electro-magnet arranged to move both contact devices simultaneously to one of their extreme positions, another electro-magnet arranged to move both contact devices simultaneously to their other extreme position, said magnets being arranged to move the contact devices to an intermediate position when energized simultaneously, means for closing the circuits through said magnets either singly or simultaneously, and supplementary means for varying either of said resistances without aflecting the other resistance.

4. The combination with an electric circuit and a variable resistance included therein, of an electrically operated contact dGYiO or varying a portion of said resistance, means for independently varying a portion of the resistance which is subject to the control of said contact devicefand supplementary means for varying another por tion of said resistance which is not subject to the control of the contact device. 4

5 The combination with two independent electric circuits .each having a variable/rcsistance included therein, of electrically-01% erated contact devices for simultaneously and similarly varying said resistances, means cofiiperating with each resistance for independently varying a portion ofthe same which is subject to the control of; the corresponding contact device, and supplementary means cooperating with each resistance for independently varying another portion of the same which is not subject to the control of said contact device.

6. The combination with an electric circuit of a variable resistance included therein and divided into a number of portions by terminals severally connected to different points of its length, a series of spring contact wires each connected to one of said terminals and comprising opposed portions separated by an intervening space, a movable blade adapted to make contact with more or less of said opposed portions, according to the position of the blade, and means for operating said blade.

7. The combination with an electric circuit of a variable resistance included therein and divided into a number of portions by terminals severally connected to different points of its length, a series of spring contact wires each connected to one of said terminals and comprising opposed portions separated by an intervening space, a movable blade adapted to make contact with more or less of said opposed portions, according to the position of the blade, two electro-magnets arranged to act on said blade in opposition to each other, and means for closing the circuits through said magnets either singly or simultaneously.

8. The combination with an electric circuit having a variable resistance included therein, of means for varying said resistance comprising a bar pivotally supported between its ends, a flexible strip secured to said bar with its ends located on opposite sides of the pivotal axis of the bar, two electromagnets having plungers connected to the ends of said strip and arranged to turn said bar in opposite directions when energized singly and to bring the bar to an intermediate position when energized simultaneously, and means for closing the circuits through said magnets either singly or simultaneously.

9. The combination with two independent electric circuits each having a variable resistance included therein, of two series of to a common operatin contact devices connected respectively to difing with the two series of contact devices for varying said resistances similarly and simultaneously, and independent means for varying either resistance without affecting the other resistance.

In testimony whereof, I have hereunto subscribed my name this second day of October, 1913.

WALTER C. REED.

Vitnesses:

WILLIAM H. WALTERS, GEORGE P. REES.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

